feat: add Database.list_tables method

google/cloud/spanner_v1/database.py

@@ -48,7 +48,8 @@
 from google.cloud.spanner_admin_database_v1 import CreateDatabaseRequest
 from google.cloud.spanner_admin_database_v1 import UpdateDatabaseDdlRequest
 from google.cloud.spanner_v1 import ExecuteSqlRequest
-from google.cloud.spanner_v1 import (
+from google.cloud.spanner_v1.table import Table
+from google.cloud.spanner_v1.proto.transaction_pb2 import (
     TransactionSelector,
     TransactionOptions,
 )
@@ -67,6 +68,11 @@
 
 _DATABASE_METADATA_FILTER = "name:{0}/operations/"
 
+_LIST_TABLES_QUERY = """SELECT TABLE_NAME
+FROM INFORMATION_SCHEMA.TABLES
+WHERE SPANNER_STATE = 'COMMITTED'
+"""
+
 DEFAULT_RETRY_BACKOFF = Retry(initial=0.02, maximum=32, multiplier=1.3)
 
 
@@ -596,6 +602,19 @@ def list_database_operations(self, filter_="", page_size=None):
             filter_=database_filter, page_size=page_size
         )
 
+    def list_tables(self):
+        """List tables within the database.
+
+        :type: Iterable
+        :returns:
+            Iterable of :class:`~google.cloud.spanner_v1.table.Table`
+            resources within the current database.
+        """
+        with self.snapshot() as snapshot:
+            results = snapshot.execute_sql(_LIST_TABLES_QUERY)
+            for row in results:
+                yield Table(row[0], self)
+
 
 class BatchCheckout(object):
     """Context manager for using a batch from a database.

google/cloud/spanner_v1/table.py

@@ -0,0 +1,36 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""User friendly container for Cloud Spanner Table."""
+
+_GET_SCHEMA_TEMPLATE = "SELECT * FROM {} LIMIT 0"
+
+
+class Table(object):
+    """Representation of a Cloud Spanner Table.
+    """
+
+    def __init__(self, table_id, database):
+        self.table_id = table_id
+        self._database = database
+
+    def get_schema(self):
+        """
+        List of google.cloud.spanner_v1.types.Field
+        """
+        with self._database.snapshot() as snapshot:
+            query = _GET_SCHEMA_TEMPLATE.format(self.table_id)
+            results = snapshot.execute_sql(query)
+            # _ = list(results)
+            return list(results.fields)